The organizers of a conference in the Houston Convention Center are evaluating the possibility of setting up a computer area where attendees can check their e-mail on computers provided by the organization. There will be one common queue for all computers and only one person uses a computer at a time. On average, there are 12 attendee arrivals per hour and the average time a person spends on the computer is 7 minutes. To ensure that waiting times are not too long, the organizers want to ensure that the utilization of the computers doesnt exceed 80 percent.

At least how many computers do they need to have?